Nickel-based metal-organic-frameworks as electrocatalysts for electrochemical oxidation of ammonia

Electrochemical oxidation of ammonia can produce hydrogen by splitting the ammonia molecules, not merely facilitating the elimination of ammonia but also augmenting sustainable hydrogen-based technological systems. However, the anode reaction is sluggish and the development of novel electrocatalysts is the major method to overcome this demerit. Herein, three kinds of Ni-based MOFs (Ni-BDC, Ni-BTC, and Ni-NH2-BDC) were prepared and used as electrocatalysts towards electrochemical oxidation of ammonia for the first time. At optimized working condition (0.5 V), Ni-NH2-BDC presents the response current density of 2.12 mA/cm2 with the current efficiency of 92.6%, both of which are significantly higher than those of Ni-BDC and Ni-BTC, indicating the better performance of Ni-NH2-BDC. EIS tests and the measurement of conductivity revealed that the good performance of Ni-NH2-BDC could be attributed to the lower charge transfer resistance at the electrode/electrolyte interface and the significantly improved conductivity which is caused by the introduction of NH2 groups.This work shed lights on the development of MOFs electrocatalysts for ammonia oxidation as well as other electrochemical reactions.